Lamar Odom -- Eating Armenian, But Still RAIL THIN

Lamar Odom ate out last night -- Armenian, of course -- but emerged from the restaurant looking scarily thin ... especially for a guy trying to make an NBA comeback after a months-long drug binge.

Lamar and some friends hit up Gavar Cuisine in Glendale, CA -- and he walked out sporting his customary Nike warmup, white tee, and interestingly ... a rosary.

LO thinks he can kick his drug habit without rehab AND return to game-shape for the upcoming NBA season, so ... if anyone could use religion it's him.

But judging by his gaunt frame ... what he really needs is a couple of double-cheeseburgers.